Biology subjects

Benowitz, L.

Publications and source records attributed to Benowitz, L..

5 recordsLinked to original sources

bioRxiv2025

Optic nerve regeneration requires the intracellular domain of LIFRa/CD118

Identifying cell-autonomous and non-autonomous factors that govern retinal ganglion cells (RGCs) ability to extend axons is an important step in developing therapies to achieve recovery after optic nerve injury. Here we report that the intracellular domain of the leukemia inhibitory factor receptor (LIFR/CD118) is essential for mature RGCs ability to regenerate injured axons independent of the cognate ligand (LIF) and other therapies. Overexpression of LIFR in adult RGCs induces neurite outgrowth in cultured RGCs and axon regeneration in vivo while strongly amplifying RGCs response to LIF itself and to unrelated growth factors. Conversely, in loss-of-function studies, down-regulation of LIFR eliminates the pro-regenerative effects of Pten deletion and other potent stimuli. LIFR bidirectionally regulates the constitutive activity of the MAP kinase pathway, in contrast to LIF itself, which primarily activates pSTAT3. Expression of a truncated LIFR lacking the extracellular domain is sufficient to promote axon regeneration and selectively increases the survival of particular RGC subtypes, placing the LIFR intracellular domain as an essential, cell-autonomous regulator of optic nerve regeneration.

neuroscience↗

bioRxiv2025

An intercellular signaling pathway in the mouse retina connects Kv2.1, GLT-1, and nitric oxide synthase 1 to optic nerve regeneration

We report here that a multicellular signaling pathway in the mouse retina targeting glutamate homeostasis and nitric oxide production is activated upon optic nerve injury and modulates reti-nal ganglion cells (RGCs) ability to mount a robust regenerative response. A novel highly sen-sitive and specific NO sensor (FL2) revealed that optic nerve injury leads to a rapid, prolonged elevation of NO in the inner retina. Amacrine cell-specific genetic deletion of the neuron-specific isoform of nitric oxide synthase (NOS1, nNOS) or the NOS1 inhibitor N(w)-propyl-L-arginine (L-NPA) suppressed optic nerve regeneration. Steps leading to NOS1 activation are shown to in-clude Kv2.1 phosphorylation and activation, reversal of glutamate uptake by the glutamate transporter GLT-1 (EAAT2), and subsequent NMDA receptor activation. Conditional knockout of the glutamate transporter GLT-1 in bipolar cells, intraocular injection of the GLT-1 blockers dihydrokainate (DHK) or WAY213613, the N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonovalerate (D-AP5), or the Kv2.1 blockers RY796 or stromatoxin all sup-pressed NO generation and strongly diminished RGCs ability to respond to Pten deletion and other factors. Thus, optic nerve injury activates a sequence of pathophysiological changes in retinal interneurons that gates RGCs ability to regenerate injured axons. Significance StatementCells use extracellular signals to coordinate responses to injury and to promote repair and re-generation. The NMDA receptor, which has a high affinity for glutamate and is functionally cou-pled to nitric oxide synthase, has the potential to mediate such responses by responding to changes in extracellular glutamate. In the mouse retina after optic nerve injury, potassium channels in retinal ganglion cells, glutamate transporters in neighboring cells, and NMDA recep-tors in amacrine cells, are all involved in a pathway that regulates the generation of nitric oxide, which we show promotes axon regeneration after injury.

neuroscience↗

bioRxiv2024

Disruption of Core Stress Granule Protein Aggregates Promotes CNS Axon Regeneration

Depletion or inhibition of core stress granule proteins, G3BP1 in mammals and TIAR-2 in C. elegans, increases axon regeneration in injured neurons, showing spontaneous regeneration. Inhibition of G3BP1 by expression of its acidic or B-domain accelerates axon regeneration after nerve injury, bringing a potential therapeutic intervention to promote neural repair in the peripheral nervous system. Here, we asked if G3BP1 inhibition is a viable strategy to promote regeneration in injured mammalian central nervous system where axons do not regenerate spontaneously. G3BP1 B-domain expression was found to promote axon regeneration in the transected spinal cord provided with a permissive peripheral nerve graft (PNG) as well as in crushed optic nerve. Moreover, a cell-permeable peptide (CPP) to a subregion of B-domain (rodent G3BP1 amino acids 190-208) accelerated axon regeneration after peripheral nerve injury and promoted regrowth of reticulospinal axons into the distal transected spinal cord through a bridging PNG. G3BP1 CPP promoted axon growth from rodent and human neurons cultured on permissive substrates, and this function required alternating Glu/Asp-Pro repeats that impart a unique predicted tertiary structure. The G3BP1 CPP disassembles axonal G3BP1, G3BP2, and FMRP, but not FXR1, granules and selectively increases axonal protein synthesis in cortical neurons. These studies identify G3BP1 granules as a key regulator of axon growth in CNS neurons and demonstrate that disassembly of these granules promotes retinal axon regeneration in injured optic nerve and reticulospinal axon elongation into permissive environments after CNS injury. This work highlights G3BP1 granule disassembly as a potential therapeutic strategy for enhancing axon growth and neural repair. SIGNIFICANCE STATEMENTThe central nervous system (CNS) axon does not have the capacity for spontaneous axon regeneration, as seen in the peripheral nervous system (PNS). We previously showed that stress granule-like aggregates of G3BP1 are present in uninjured PNS axons, and these slow nerve regeneration. We now report that CNS axons contain G3BP1 granules, and G3BP1 granule disassembling strategies promote axon regeneration in the injured sciatic nerve, transected spinal cord with a peripheral nerve graft, and injured optic nerve. Thus, G3BP1 granules are a barrier to axon regeneration and can be targeted for stimulating neural repair following traumatic injury, including in the regeneration refractory CNS.

neuroscience↗

bioRxiv2022

Full-length optic nerve regeneration in the absence of genetic manipulations

The inability of mature retinal ganglion cells (RGCs) to regenerate axons after optic nerve injury can be partially reversed by manipulating cell-autonomous and/or -non-autonomous factors, among which are neuroimmune interactions. We report here that preconditioning resulting from a mild lens injury (conditioning LI, cLI) prior to optic nerve damage induces far greater axon regeneration than LI or the pro-inflammatory agent zymosan after nerve injury or preconditioning with Zymosan. Unlike other instances of immune-supported regeneration, cLI is unaltered by depleting mature neutrophils, T cells or blocking receptors for identified inflammation-associated growth factors (Oncomodulin, SDF1, CCL5), and is only partially diminished by suppressing peripheral monocyte recruitment. Repeated LI leads to full-length optic nerve regeneration, and pharmacological removal of local resident macrophages with the colony stimulating factor 1 receptor (CSF-1R) inhibitor PLX5622 enables some axons to re-innervate the brain in just 6 weeks. Thus, cell non-autonomous interventions not involving genetic manipulations can induce high levels of optic nerve regeneration, paving the way to uncover potent, translatable therapeutic targets for CNS repair.

neuroscience↗

bioRxiv2018

Combined inhibition of apoptosis and necrosis promotes transient neuroprotection of retinal ganglion cells and partial axon regeneration after optic nerve damage

Retinal ganglion cell (RGC) death is the hallmark of glaucoma. Axonal injury is thought to precede RGC loss in glaucoma, and thus studies using an optic nerve (ON) crush model have been widely used to investigate mechanisms of cell death that are common to both conditions. Prior work has focused on the involvement of caspases in RGC death, but little is known about the contribution of other forms of cell death such as necrosis. In this study we show that receptor interacting protein (RIP) kinase-mediated necrosis normally plays a role in RGC death and acts in concert with caspase-dependent apoptosis. The expression of RIP3, a key activator of RIP1 kinase, as well as caspase activity, increased following ON injury. Caspase inhibition alone failed to provide substantial protection to injured RGCs and unexpectedly exacerbated necrosis. In contrast, pharmacologic or genetic inhibition of RIP kinases in combination with caspase blockade delayed both apoptotic and necrotic RGC death, although RGCs still continued to die. Furthermore, inhibition of RIP1 kinase promoted a moderate level of axon regeneration that was only minimal affected by caspase inhibition. In conclusion, multiple approaches are required for effective RGC death prevention and axonal regeneration. Further studies are needed to elucidate more effective long term strategies that can lead to sustained neuroprotection and regeneration.

neuroscience↗